If you want to find Peter Vitousek in his lab, the first thing you have to do is go to Hawaii. After that, it gets tricky, because Vitousek's lab isn't in the state--it is the state. The Stanford University ecologist has devoted his career to studying the earth's metabolism and life cycles, zeroing in on how the intricate machinery of its forests is altered by people and the introduction of new plants and animals. "Peter is a real visionary," says marine ecologist Jane Lubchenco of Oregon State University. "It's unusual to have someone who is simultaneously interested in the big picture...